Yes, valuations on startups are getting out of hand -- in part because everyone and their brother has suddenly decided it's cool to be an angel investor.

But this is certainly not a universal "Tech Bubble 2.0."

Why not?

Because the froth is limited to the early-stage venture market and, possibly, a few high-profile acquisition candidates. Most public-market valuations are still completely reasonable.

Take Google (GOOG), for instance. It's trading at 24X earnings. (And that's actual trailing earnings, not some analyst hallucination about the future).

Or Apple (AAPL)--the hottest company in the universe. Apple is trading at 21X earnings. Back in the actual tech bubble, in the late 1990s, there was basically no tech company on earth you could buy for 21X earnings, let along the hottest one in the universe.

Microsoft (MSFT), meanwhile, is trading at 12X earnings.

Sure, Netflix (NFLX) and OpenTable (OPEN) and a couple of other hot stocks have gotten pricey, but these companies are absolutely killing it. Except in the depths of a global financial panic, companies that are growing as fast and executing as well as Netflix and OpenTable always have high multiples. And these multiples aren't even close to what you'd see in an actual bubble.

And then there's Groupon, the company that has allowed every idiot in the street to say confidently that tech investors have gone stark-raving mad again.

Groupon is now generating a run-rate of $2 billion in revenue, up from less than $1 billion earlier this year. So Google offered 3X Groupon's run-rate revenue. Assuming Groupon grows at all next year (likely), Google's offer might amount to 2X 2011 revenue. Say all you want about how Groupon is more dependent on "people" and "marketing" than some of technology's golden children. There's nothing remotely bubble-like about that valuation.

So, yes, the angel market's frothy. And as has happened every time the venture market has gotten frothy -- such as 2007, when people were also talking about Bubble 2.0 -- it will eventually crater, as the Tom, Dick, and Harry angel investors realize that it's actually harder than it looks.

But then it will come roaring back.

The valuations in the broader tech market, meanwhile, are miles from being in bubble territory.